Goodrum, Matthew R. (2008). "Questioning Thunderstones and Arrowheads: The Problem of Recognizing and Interpreting Stone Artifacts in the Seventeenth Century". Early Science and Medicine. 13 (5): 494. doi:10.1163/157338208X345759.
Goodrum, Matthew R. (2008). "Questioning Thunderstones and Arrowheads: The Problem of Recognizing and Interpreting Stone Artifacts in the Seventeenth Century". Early Science and Medicine. 13 (5): 495. doi:10.1163/157338208X345759.